Designed for the Intel Pentium 4 processor
400MHz system bus
82845 MCH/82801BA I/O controller hub
Supports up to 2.0GB PC1600/PC2100 DDR SDRAM
Dual USB controllers for up to four ports
AGP 4X interface
Two Ultra ATA/100 controllers
LAN connect interface for home phoneline networking or 10/100Mbps Ethernet
The DDR version of the 845 chipset is the same chipset that was introduced earlier this year. Just as DDR memory controllers from VIA and SiS are backwards compatible with PC133 SDRAM, Intel's 845 memory controller is also backwards compatible with this memory type. However, there is one key difference, while running with PC133 memory the 845 chipset can address up to 3GB of memory, however, in DDR mode 845 can only address 2GB of DDR memory. While 2GB may sound like a lot at first, 2GB is hardly enough for the server/workstation market, and also falls short of DDR chipsets from VIA and SiS.
In addition, the 845 chipset only officially supports up to two DIMM sockets, while many motherboard manufacturers provide three DIMM sockets, you won't be able to use all three DIMM sockets with double-sided DDR memory modules. If you plan to use all three sockets, you'll instead have to use single-sided modules on DIMMs two and three, while DIMM socket one can use double-sided or single-sided memory.
The I/O controller hub of the 845 chipset contains dual USB controllers for support of up to four USB devices, and dual ATA/100 controllers. In comparison, SiS and VIA Pentium 4 chipsets support up to six USB ports and in the case of VIA's P4X266A, ATA/133 hard drives are natively supported.
Overall, we find the memory limitations of the 845 chipset to be our largest gripe. Two DIMM sockets just isn't enough for any performance enthusiast, and with some motherboard manufacturers offering three DIMM sockets on their products, end users may end up confused. After reading this, you shouldn't be one of those users.